Process for the production of synthetic isoparaffinic oil



A. c. BYRNs 2,435,708 PROCESS FOR THE PRODUCTION OF SYNTHETIC ISOPARAFFINIC OIL Feb. 1o, 1948.

Filed June r8, 1942 2 Sheets-Sheet l INVENTOR.

A4144 C. Ene/v5,

um N

ATTORNEY.

A. c. BYRNs 2,435,708

PROCESS FOR THE PRODUCTION OF SYNTHETIC ISOPARAFFINIC OIL Feb. 10, 1948.

Filed June `8, 1942 2 Sheets-Sheet 2 INVENTOR.

ATTORNEY Patented Feb. 10, 1948 f VFieri:

PROCESSQFQR. THE PRODUCTION. '0F' SYNTHETIGISOPARAFFINICOIII Alva (lllyrnsg` BalbsdVerdeseEstatesa ,allf'.,.f.ase

. signor to Unici-r Oil Compamrrof Gallfornia, Angeles-,5. Calif., a corporation. of:Galiomia Application A.furie-li",- 1942;' Serial l-lo.5fi4'6;195-y lixlaimsr `(Cl. Z60fv6832f4ei1 l# This applicationv relates to a process. for produce tionA off 'synthetic light f oils-3 morel particularly= to arralkyla-tion processl for the; production of'fpredominately isoparaiiinie oils boiling largel'yfin the-range of '40'0"`F.' to -800'o F.

Ilitherto processesinvolving production o't l"isoparailinicmaterial'by alkylation reactions-'have beenv devotedfallmost exclusively to the 'manufacture of light alkylate"`boiling in the gasoline range, particularly in the aviationgasolinelboil ing; range4 of f aboutv 100" to"3'00 E vMany ingenious inventionsy havefbeen madeftofsuppress the production of hea-vier'material'isuchasim termed-iatef alkylate, -for example material boil# ingfroln about 300 F. to 400- F. and`l generally used onlyfor `motor fuel blending,` andi-heavy alkylate boiling above 400 F. and frequently considered-of no valueexcept as crackingfstock; Many of'these inventions-alsofhave'had'ibenefici'al effects on catalyst life andk quality ofthe light ailiyl'ate.

It is the object ofthe present invention to pro# vide novel modifications in the presentvalkylation procedures whereby the production of' *heavy al# kylate; which has been foundto `have valuable applicationin insecticide' sprays; hydraulic oil's. etc., is'notsuppressed, but enhanced'oreven'made the primary aim of "the process, withoutlhaving objectionable efiects on catalysblife-andtquality ofthe light alkylate which mayv be lproducedconcurrently. I

Briefly theinvention resides in separatingA4 the desired, heavy alkylate from the product' ol" a primary alkylation process and realkylating4 lower boiling fractions from" the prima-ry alkylatio'n either with the' same olefin stock usedfin the primary alkylation or with a secon-dL olefin 'stock'. In one modification of the invention, using'the same olefin' feedstock in a single-stage process andassuming both light alkyliate-.andiheavyyale kylate productsarare, desiredv as f products; these fractions aregseparated Afrom the total ,alkylate production'. leaving-.5 the,` intermediatefv al-k-ylate whichT is.i recycled. to; produce. additional heavy alkylate.. If the..light.alkylate.is not desired.. a.s

aproduct', itmay alsoberecirculated.with ineinterlnediatez .alkyla-te.. In. .another 4 modification of the inventionany desiredfraction of the. original total'alkylatejboiling. below theboiling range oi the desiredlheavyalkyl'ate is subjected to a 'secjond alkylation with asecond olefin stoclrwhich may orv may'not be the same as theori'ginal'olefin stock, and-"the product of thefsecond alkylation -is` fractionated" tof produce heavy alkylate; for 'example boiling" above i 400 F. and lighter* fractions 'which' mayfornot bere'circulated' throng-lithosecondfalkylation stage'.

To illustrate the invention, certain aspects are shown-v in the accompanying drawings, which alkylation/-offisobut'ane'- with mixed butenes; and: pentenes usln'g-fcon'centrated "sulfuric-acid1'assthe catalyst;y and :wherein Fig. 1 illustrates aoneestage: operationg. and. Figf fillustrates-aftwoestage operation.. Referring to Fig. 1f; 'an isoparafiinl stream, er. g: isobutane; 'fiowing through line. I controllediby valve-2; isffmixedrwith anrfolefin strearm.` e. g.' a mixed"1 butenediente-neA stream passing through line 3"c'onti"ollel byvalve Il.' The mixture of iso. paraffin and oleii'ns 'is-.passed through line'V 5: and pumpfli controlled by valve-l; and-thence 4through lines BI-and: Sito-reactor I0. A1 recycle stream of isoparaflinf,` in this example `is'oloutane and ine termediatea1ky1atel isfintroduced also.` intoV line 8'througlir-'iinel I' and pump I'2 'controlled' by valve IPB; andflows-tlireuglli lines-'8Y and 9 to reactor V-Illl Another 'stream'. containing catalyst,V Hz'SO'4 in thisexample, is introduced also into line 9 through line lIlandfpump-|25-controlled byvalve I6, and flows with the otherftwo streams through line 9 tarea-eter I Il. Prom reactor loywhich is equipped for propercoolingandmixingfoi` catalyst; reactants; andrec'ycley oil', two streams containing both'vcatalyst andalkylated product are drawn. Gnefst'reamispassedlthrough line Il into catalyst seliaratorY I8,"wher'e it i's separated into a catalyst phase-and"an oil-"phasev The catalyst phase is passedthrough line Illlf valve 201, and lines Hand 22 tolne Il aheadofpump |51 Spent catalyst mayYb'e'withdrawn fromV line I-'9 through line 23 andj'valver2lf and new Icatalystrnay be introduced into-lineH22'through-valve'25and` line 26, in order to-rnaintainvthe catalyst at-proper strength. The second. streamiirom reactor lI 0` is passed through line, ZIf'and'valve'Zaalso15o-'line I4--ahead of pump Iii The'oi'lph'aseirom separator I8-` ispassed successively throug-ljline-Z 9l `to. oil` purifierfsystem 30," Whereitfisj'freed from traces of'fcatalyst, by

' caustic Washing-inthisexample; The oil from purier 30 .is passed?successively4 through line 31"' to' ap'seri'es of three fractionatingtowers 32, 33; and-3l; equippcdwithfeed preheaters 35; 36, andfllli 'bottomsreboil'ers 38, 39 `and 40; overhead'vaporcondenserstl; #2', and143; and reflux returnl lines if; 'l5-L and-46; tt'ed with control valvesll; 481' andfgrespectively. Col-umn'32 is 'operat-'edso-asV to produce an overhead 'consistii'ngtprincipall'y'-otthe lisoparailln feedstock, isotbutane: infithisxfexample, which is, passed through line 50, condenser 4l, line 5l and valve 52 to recycle line Il ahead of pump I2. The bottoms from column 32 pass through line 53 and pump 54 controlled by valve 55 through preheater 36 to column 33; and the bottoms from column 33 pass through line 56 and pump 51 controlled by valve 58 through preheater 31 to column 34. The overhead from column 33 passes through line 59, condenser 42, line 60 and control valve 6| to storage. This overhead "light alkylate consists in this example of liquid alkylate boiling below about 300 F., which may be fractionated for removal of normal butane and normal pentane if present, and blended into high quality aviation gasoline. The overhead from column 34 passes through line 62, condenser 43, line 63 and control valve 64 to line El and Il, ahead of pump I2. This overhead intermediate alkylate consists in this case of material boiling above 300IF. and below the initial boiling point ofthe desired heavy alkylate bottoms from this column (34) which latter material is drawn oil?v through line 65 and valve 66. Y w 1 The novel feature of this process lies lin the recirculation of an intermediate alkylate fraction separated from the total alkylate product, to produce the desired heavy alkylate. If a larger ratio of heavy alkylate to light alkylate is deslred, part f the light alkylation production may be recycled with the intermediate alkylate; and if no light alkylate is desired, fractionating columns 33 and 34 may be eliminated by modifying the operation of column 32 so as to take overhead the light alkylate and the intermediate alkylate as well as the isobutane. is then recirculated, and the bottoms constitute the heavy alkylate production. It should be noted that such recirculation of isoparafiinic material does not tend to decrease Acatalyst life or quality of product. Heavy alkylate samples have been prepared as above by reacting light alkylate, intermediate alkylate, or total alkylate with butenes and pentenes in the proportions of about volumes isoparain t0 one of olefin in the presence of 98% `H2804 at temperatures between 32 .i i

F. and 140 F., and the products, after fractionation and acid-clay treatment, where necessary, have been found to be excellent ingredients for insecticide sprays, hydraulic oils, and the like. It has been found that in general, relatively low ratios of isoparaiiln to olefin feed stocks, sulfuric acid catalyst strengths below sayV 95%, and reaction temperatures above about 50 F., tend to increase the production of heavy alkylate.

Another phase of the invention is shown in Figure 2 which illustrates a two-stage alkylation process, each stage having similar equipment to that of the single stage equipment of Figure l. For convenience in reference, the various pieces of equipment of Figure 2 are numbered to correspond with the numbering ofFigure' 1 using additional letters a and b to' distinguish first This entire overhead stage and second` stage equipment respectively.

ate ls charged to the reactor of the second stage. The single fractionating column of the second stage is used to produce a bottoms fraction of heavy alkylate of the desired initial boiling point which is combined with the heavy alkylate produced in the first stage, and an overhead stream which is recycled. The novelty here also resides in recirculation of an isoparaiiinic fraction from a previous alkylation, freed from the isoparafnic feed material andthe desired heavy alkylate, but in this instance employment of a two stage process permits use of dilerent olen feed stocks, different catalysts, temperatures, iiow rates, etc., in the two stages. Heavy alkylate fractions boiling in the range 400 F. to 800 F. have been prepared by reacting intermediate alkylate and commercial di-isobutylene in a volume ratio of 5 to 1 respectively with 98% sulfuric acid at temperatures between 32 F. and 140 F., and these products have been found suitable for application in'spray oil and other compositions as were the similar fractions from the single stage process above. Many modifications of the above vinvention are possible. For example, in the two stage process, the olefin feed stock may be a polymer of a normally gaseous olen, cracked wax olei'lns, or a mixture of hydrocarbons comprising olens and aromatics such as cracked or dehydrogenated petroleum fractions; the isoparaflinic feed stock may be mixed isoparaffins or mixtures of normal and isoparailins; the boiling ranges of the light alkylate, intermediate alkylate, and heavy alkylate fractions may be modifications of the above approximations; the catalysts may be sulfuric acid, hydrofluoric acid, aluminum chloride, or any other alkylation catalyst using different catalysts in the two stages if desired; the operating conditions may be varied to suit the stocks, catalysts and equipment; and the equipment may be modified to suit the catalysts, etc. Where the olefin feed stock for the second stage is a cracked gasoline, for example,'it may be desirable to use two fractionating columns in the second stage instead of one, taking a gasoline overhead fraction, at least partially freed from aromatics and oleiins, in the first column and sending the bottoms to the second column, where the desired heavy alkylate is taken as a bottoms fraction and the recycle isoparaiiin stream is taken overhead. When the olefin fraction sent to the second stage contains aromatic hydrocarbons, there is likely to be an appreciable quantity of alkylated aromatics in the heavy alkylate production. In case this is undesirable such stocks should be avoided. The heavy alkylate production may be treated with sulfuric acid, clay. caustic, zinc chloride, etc., and fractionated to obtain premium grade stocks for production of spray oils, hydraulic oils, Dieselv fuels, etc., boiling. substantially within the range 400 F. to 800 F.

'It has been observed that in general synthetic isoparafnic oils have some tendency to deteriorate in color and odor, or increase in acidity on continued storage, particularly if the storage 4'conditions involve exposure to oxygen, heat, or catalytic surfaces. However, the addition of an antioxidant, particularly one of the eillcient al- -kylated or arylated aminophenols, is usually veiy effective in retarding such deterioration. For example a heavy alkylate was fractionated to obtain a material boiling approximately from 450 to 600 F., and this fraction was treatedwith H2SO4 and clay, in aconventional manner to obtain a stock for the following stability experiments:

One portion of the stock, containing no inhibitor, was placed in light storage in a 4 oz. clear glass bottle with a loose cotton stopper and exposed to sunlight for two weeks. A second portion, likewise uninhibited was placed in dark storage in a loosely capped tinned can for two Weeks at a temperature of about 160 F. Both samples showed an increase of 0.2 to 0.3 mg. KOI-I per g. in acid number and development of pronounced odor. Serious color degradation also occurred in the dark storage test. Three similar pairs of samples of the same stock, containing 0.0025% BAP (monobenzyl p-aminophenol), 0.025% Universal Oil Products C0. Inhibitor No. 5, and about 0.01% hydroquinone, respectively showed no appreciable degradation in acid number, odor, or color in the above dark storage test. In light storage, the BAP was similarly entirely effective; the U. O. P. No. 5 protected the acid number and odor while degrading the color appreciably, and the hydroquinone had apparently no appreciable effect at all.

It will be apparent to those skilled in the art that many modications in addition to those mentioned above may be made Without departing from the scope of the invention as defined by the following claims.

I claim:

1. A continuous two-stage process for production of synthetic isoparainic oils boiling largely in the range 400 F. to 800 F., comprising a. first stage in which an olefin feed stock comprising normally gaseous olens is reacted with an isoparainic feed stock containing isobutane in molal excess in the presence of alkylation catalyst and the reaction product is fractionally distilled to obtain an isobutane fraction, which is recirculated, the desired heavy alkylate fraction boiling largely between 400 F. and 800 F., as a residual fraction which is not recirculated and an isoparainic intermediate fraction having a boiling range between about 300 F. and 400 F.; and a second stage in which said intermediate fraction free from those materials comprising the isoparafnic feed stock employed in the first stage is reacted with an olefin which is present in lower molal proportions than the isoparaflin,

6 employing an oleflnic stock containing no aromatic hydrocarbons, and carrying out the reaction in the presence of an alkylation catalyst; and a third step in which the catalyst free product is fractionally distilled to obtain the desired fraction, boiling approximately within the range 400 F. to 800 F., as a residual fraction which is not recirculated and one or more lower boiling fractions at least one of which is recirculated to the second stage reactor.

2. A process according to claim 1 in which the olen stock used in the second stage is a polymer of a normally gaseous olen; the catalyst used in the first stage is concentrated sulfuric acid of t-o 110% strength; and the reaction temperature for the rst stage is between 32 F. and F.

3. A process according to claim 1 in which the olefin stock used inthe second stage is a product from cracking of paraffin wax; the catalyst used in the iirst stage is concentrated sulfuric acid of 80% to 110% strength; and the reaction temperature for the :lirst stage is between 32 F. and 140 F.

4. A process according to claim 1, in which the catalyst employed in each stage is sulfuric acid having a concentration between 80% and 95% by weight, the ratio of isoparai'lin to olen to each stage lies between about 1:1 and 5:1, and the reaction temperature in each stage is between about 32 F. and 50 F.

ALVA C. BYRNS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,286,504 Parker June 16, 1942 2,260,944 Goldsby et al. Oct. 28, 1941 2,256,615 Hederhorst Sept. 23, 1941 2,211,747 Goldsby et al. Aug. 13, 1940 2,322,482 Stahly et al. June 22, 1943 FOREIGN PATENTS Number Country Date 515,039 Great Britain Nov, 24, 1939 515,367 Great Britain Dec. 4, 1939 

